Bitcoin has proven to be the best investment over the years, and nobody with a good knowledge of Bitcoin and cryptocurrency in general can deny the fact that Bitcoin is not the best investment. Considering what early investors have made from Bitcoin since its exitance, I don't think it can be compared to any other investments, such as real estate, gold and others like that.
I think the best investment will depend on each person's needs. If you are looking for high returns and are willing to take risks then bitcoin is clearly the best investment. But for investors who have billions of dollars in hand and what they need is a safe asset, it is clear that bitcoin is not suitable for them, gold or real estate will be more suitable and they will be the best investment for them.
Just because you invest in bitcoin and it's best for you doesn't mean you can impose your thoughts on others. Each person's needs and thoughts are different.
Yes, I agree with you that some people have quit their Bitcoin investments because it is not meeting their expectations. They thought it would make them rich quickly, but that is not happening. Any investment that promises to make someone rich quickly in the short term usually involves high risk, which I would consider similar to gambling. When someone engages in such investments, they are likely to lose easily. If more people can stop thinking that Bitcoin will make them rich quickly and instead view it as a long term investment, it would be a great idea and could lead to significant benefits.
Bitcoin is not a get rich quick scheme like gambling but it is clearly a way to get rich faster than any other traditional form of investment. The reason you, me and everyone here choose bitcoin is because we believe that we will be able to make high profits from bitcoin in the coming years. Meanwhile, if we invest in gold or real estate, it will take more time. As you said: bitcoin is the best investment because no investment gives better returns than bitcoin.